KAURI DIEBACK

Kauri Dieback Phytophthora taxon Agathis

Kauri dieback is the deadly kauri disease caused by Phytophthora taxon Agathis (or PTA). It is the greatest single threat to kauri survival after 50 million years. Ironically it is caused by a type of pathogenic fungus, Phytopthera that kauri has historically been resistant to.

Following DNA studies, this fungus-like disease was formally identified in 2008 as a distinct and previously undescribed species of Phytophthora. Kauri dieback is specific to New Zealand kauri and can kill trees of all ages.

Waipoua Forest Trust is fully supportive of efforts to understand and control this disease, and to protect our kauri forest from it into the future. Currently we are planning strategies to protect the Waipoua Forest from PTA, and have already completely reconstructed our nursery operation to ensure our seedlings are free from contamination.

Dieback attacks through microscopic spores in the soil that infect kauri roots and damage the tissues that carry nutrients within the tree. Infected trees show a range of symptoms including yellowing of foliage, loss of leaves, canopy thinning, dead branches and lesions that bleed gum at the base of the trunk.

Some infected trees can show canopy dieback and even be killed without any gum showing on the trunks as kauri dieback also acts as a severe root rot below ground.

Nearly all infected kauri die. So far, kauri dieback has killed thousands of kauri in New Zealand.

Scientists are currently working to find control tools for this disease but there is no known treatment at this time.

Some of the first research undertaken looked at what species might be affected by this disease and the impact on NZ kauri. A range of exotic plant species (eg. Pinus radiata and oak) and native plants were inoculated with the disease. NZ kauri saplings were the only plants that died in this experiment and no obvious symptoms were shown by any other species tested.